This invention relates generally to power supply switching circuits, and more particularly to a solid state, low power latching type switching circuit which connects and disconnects battery power to and from a load.
Power supply switching circuits are generally known and take many forms. For example, such apparatus has usually found application where power supplied to a circuit from a primary source is switched to a secondary source in response to a predetermined condition, typically the failure of the primary power source. Heretofore, a mechanical magnetically latching relay has been known to be utilized for interconnecting the power sources to the load but such a device inherently suffers from being sensitive to vibration and electromagnetic noise. In such instances, the relay contacts can be forced into an undesirable neutral state which virtually renders the switching control useless. More recently, however, power supply switching arrangements have been developed where solid state circuitry is used as an electronic relay to control and connect one or more power supplies to a load in order to, among other things, overcome the vibration and noise problem.
It is an object of the present invention, therefore, to provide an improvement in circuitry for connecting a power supply to a load.
It is another object of the invention to provide an improved solid state latching type of control circuit for connecting a dual battery power supply to a load while consuming a minimal amount of power.
And yet a further object of the invention is to provide a solid state latching control circuit which replaces a mechanical magnetically latching relay for controlling power supply voltages of both positive and negative polarities from a pair of DC batteries utilized concurrently.
And it is yet another object of the invention to provide a low power latching control circuit for dual battery power supply which exhibits relatively high electrical noise immunity while being insensitive to mechanical vibrations.